This study is a double-blind, randomized, placebo-controlled, sequential group design with an unblinded dispenser(pharmacy). The purpose is to determine the safety, tolerance and pharmacokinetics of ascending single oral doses of Sirolimus in pediatric patients with stable, chronic renal failure receiving hemodialysis. Sirolimus, a natural fermentation product (macrolide antibiotic) has demonstrated potent immunosuppressive activity in a number of animal heart and renal allograft models.